Yes You can use it.

Yes Admin can add custom fields as many as they want

Kolkata Page is build up with latest trends and coading standards. Yes it's fully customization with visual composer

Kolkata Page is fully customization you can create whatever you want.

Yes Each user will have there own page and dashboard . And its compatible with commerce.

Yes This is Google AdSense supported.Even you can use Image ads if you don't want to use Google AdSense.

Yes Kolkata Page come's with complete Messages solution. You just need to go to your dashboard to see all conversations

Yes From theme options you can select add will be approved automatically or on approval

All Registered user can post free ads, And IF user want to post featured ads then user must need to purchase a plan.

Yes from back end you can change currency options